Question
Find the roots
x1=−81−814i,x2=−81+814i
Alternative Form
x1≈−0.125−0.467707i,x2≈−0.125+0.467707i
Evaluate
64x2+16x+15
To find the roots of the expression,set the expression equal to 0
64x2+16x+15=0
Substitute a=64,b=16 and c=15 into the quadratic formula x=2a−b±b2−4ac
x=2×64−16±162−4×64×15
Simplify the expression
x=128−16±162−4×64×15
Simplify the expression
More Steps

Evaluate
162−4×64×15
Multiply the terms
More Steps

Multiply the terms
4×64×15
Multiply the terms
256×15
Multiply the numbers
3840
162−3840
Evaluate the power
256−3840
Subtract the numbers
−3584
x=128−16±−3584
Simplify the radical expression
More Steps

Evaluate
−3584
Evaluate the power
3584×−1
Evaluate the power
3584×i
Evaluate the power
More Steps

Evaluate
3584
Write the expression as a product where the root of one of the factors can be evaluated
256×14
Write the number in exponential form with the base of 16
162×14
The root of a product is equal to the product of the roots of each factor
162×14
Reduce the index of the radical and exponent with 2
1614
1614×i
x=128−16±1614×i
Separate the equation into 2 possible cases
x=128−16+1614×ix=128−16−1614×i
Simplify the expression
More Steps

Evaluate
x=128−16+1614×i
Divide the terms
More Steps

Evaluate
128−16+1614×i
Rewrite the expression
12816(−1+14×i)
Cancel out the common factor 16
8−1+14×i
Use b−a=−ba=−ba to rewrite the fraction
−81−14×i
Simplify
−81+814i
x=−81+814i
x=−81+814ix=128−16−1614×i
Simplify the expression
More Steps

Evaluate
x=128−16−1614×i
Divide the terms
More Steps

Evaluate
128−16−1614×i
Rewrite the expression
12816(−1−14×i)
Cancel out the common factor 16
8−1−14×i
Use b−a=−ba=−ba to rewrite the fraction
−81+14×i
Simplify
−81−814i
x=−81−814i
x=−81+814ix=−81−814i
Solution
x1=−81−814i,x2=−81+814i
Alternative Form
x1≈−0.125−0.467707i,x2≈−0.125+0.467707i
Show Solution
